May 5 - Online diamond retailer Blue Nile posted a quarterly profit that met market estimates but forecast second-quarter earnings below analysts' expectations, sending its shares down as much as 5 percent in extended trade.

Blue Nile's website

The company sees second-quarter earnings of 19-21 cents per share, while analysts on average were expecting 22 cents per share, according to Thomson Reuters I/B/E/S.

The company sees sales of $82-$84.5 million, below analysts' expectation of $84.6 million.

First-quarter net income was $2.4 million, or 16 cents a share, compared with $2.4 million, or 16 cents a year ago.

Net sales rose 8.3 percent to $80.2 million.

Analysts on average had expected a profit of 16 cents a share, on revenue of $77.7 million.

Shares of the company were trading at $53 in after market trading. It closed at $55.79 on Thursday on Nasdaq.

(Reporting by Arpita Mukherjee in Bangalore; Editing by Jarshad Kakkrakandy)